Individually, Republican Senator Marco Rubio and Democratic Senator Richard Blumenthal wrote to Super Micro's chief executive, Charles Liang, and asked him to provide by October 17 information including when the company first became aware of the report and whether and how it investigated.

"If this news report is accurate, the potential infiltration of Chinese backdoors could provide a foothold for adversaries and competitors to engage in commercial espionage and launch destructive cyber attacks," the senators said in their letter, which was seen by Reuters.

Apple's top security officer, George Stathakopoulos, told Thune and other members of Congress in a letter on Sunday that the company had found no sign of mistrustful transmissions or other evidence that it had been getting into a sophisticated attack on its supply chain.